Head chip

Abstract

A head chip has a plurality of chambers provided in a piezoelectric plate, nozzles at ends of the chambers, electrodes in the chambers for applying a voltage to discharge ink from the nozzle openings, and an ink chamber plate joined to the piezoelectric plate for defining a common ink chamber communicating with the plural ink chambers, and having a partitioning portion for partitioning the chambers and the common ink chamber and communicating holes for defining a pump length according to a distance from the nozzle openings, so that converging time during which pressure in the ink chambers attenuates may be reduced to enable high speed printing without deteriorating ink discharge characteristics. In addition, by providing the communicating holes at equal intervals the converging time does not fluctuate even if the discharge amount is controlled based on the shape of the nozzle openings.

What is claimed is:  
     
       1. A head chip comprising: 
       a substrate in which a plurality of individual ink chambers are formed for containing ink;  
       a nozzle opening in communication with one end of each individual ink chamber for discharging the ink contained within the individual ink chambers;  
       an electrode within each individual ink chamber for changing a volume within the respective individual ink chambers according to a driving voltage applied thereto to cause the ink in the respective individual ink chambers to be ejected through the nozzle opening;  
       an ink chamber plate forming a common ink chamber in communication with the respective individual ink chambers, the ink chamber plate being joined to the substrate; and  
       a partitioning member for creating a partition between the individual ink chambers and the common ink chamber and having a plurality of communicating holes opening to each of the individual ink chambers including first communicating holes for defining a pump length of the respective individual ink chambers according to a distance of the first communicating holes from the respective nozzle openings.  
     
     
       2. A head chip according to  claim 1 ; wherein the plurality of communicating holes are spaced apart by a distance equivalent to the pump length. 
     
     
       3. A head chip according to  claim 2 ; wherein the substrate is formed of a piezoelectric ceramic plate, and the individual ink chambers comprise grooves formed in the piezoelectric ceramic plate to communicate with the common ink chamber at openings in the substrate at ends of the individual ink chambers opposite the one end at which the nozzle openings are formed in a longitudinal direction of the individual ink chambers. 
     
     
       4. A head chip according to  claim 2 ; wherein the substrate comprises a base plate and sidewalls formed of a piezoelectric ceramic arranged on the base plate at a predetermined interval to define the individual ink chambers between the sidewalls, and the individual ink chambers and the common ink chamber communicate with each other at an end of the individual ink chambers opposite the one end at which the nozzle openings are formed in a longitudinal direction of the individual ink chambers. 
     
     
       5. A head chip according to  claim 1 ; wherein the ink chamber plate has separate members forming the partitioning member and the communicating holes. 
     
     
       6. A head chip according to  claim 5 ; wherein the substrate comprises a piezoelectric ceramic plate, and the individual ink chambers comprise grooves formed in the piezoelectric ceramic plate in communication with the common ink chamber at openings in the substrate at ends of the individual ink chambers opposite the one end at which the nozzle openings are formed in a longitudinal direction of the individual ink chambers. 
     
     
       7. A head chip according to  claim 5 ; wherein the substrate comprises a base plate and sidewalls formed of a piezoelectric ceramic material arranged on the base plate at a predetermined interval to define the individual ink chambers between the sidewalls, and the individual ink chambers and the common ink chamber communicate with each other at an end of the individual ink chambers opposite the one end at which the nozzle openings are formed in a longitudinal direction of the individual ink chambers. 
     
     
       8. A head chip according to  claim 1 ; wherein the substrate is formed of a piezoelectric ceramic plate, and the individual ink chambers comprise grooves formed in the piezoelectric ceramic plate to communicate with the common ink chamber at openings in the substrate at ends of the individual ink chambers opposite the one end at which the nozzle openings are formed in a longitudinal direction of the individual ink chambers. 
     
     
       9. A head chip according to  claim 1 ; wherein the substrate comprises a base plate and sidewalls formed of a piezoelectric ceramic arranged on the base plate at a predetermined interval to define the individual ink chambers between the sidewalls, and the individual ink chambers and the common ink chamber communicate with each other at an end of the individual ink chambers opposite the one end at which the nozzle openings are formed in a longitudinal direction of the individual ink chambers. 
     
     
       10. A head chip according to  claim 1 ; wherein the plurality of communicating holes further comprise a second communicating hole formed near an end of the respective individual ink chambers opposite the nozzle openings. 
     
     
       11. A print head chip comprising: a substrate defining a plurality of individual ink chambers for containing ink, each individual ink chamber having a nozzle at one end and an electrode for applying a voltage to the respective individual ink chamber to cause the ink to be ejected through the nozzle; a common ink chamber in communication with each of the plurality of individual ink chambers; and a partitioning member for creating a partition between the individual ink chambers and the common ink chamber and having a plurality of communicating holes opening to each of the respective individual ink chambers including first communicating holes for setting a pump length of the respective individual ink chambers based on a distance of the respective first communicating holes from the respective nozzles. 
     
     
       12. A print head chip according to  claim 11 ; wherein the substrate comprises a piezoelectric substrate, the individual ink chambers comprise elongated grooves formed in the piezoelectric substrate, and the electrodes are disposed on sidewalls of the grooves in a longitudinal direction thereof such that a voltage applied by a respective electrode deforms a corresponding individual ink chamber to cause the ink contained therein to be ejected through the nozzle. 
     
     
       13. A print head chip according to  claim 12 ; wherein the substrate comprises a base plate and piezoelectric members provided on the base plate spaced by a given interval to define the respective individual ink chambers, and the electrodes are disposed on sidewalls of the piezoelectric members in a longitudinal direction thereof such that a voltage applied by a respective electrode deforms a piezoelectric member of a corresponding individual ink chamber to cause the ink contained therein to be ejected through the nozzle. 
     
     
       14. A print head chip according to  claim 11 ; wherein the plurality of communicating holes are positioned at a desired location to set a pump length of the respective individual ink chambers at a value required to achieve a desired printing speed. 
     
     
       15. A print head chip according to  claim 11 ; wherein the plurality of communicating holes further comprise a second communicating hole formed near an end of the respective individual ink chambers opposite the nozzles. 
     
     
       16. A print head comprising: a head chip having a plurality of individual ink chambers for containing ink and a common ink chamber in communication with the plurality of individual ink chambers; a nozzle plate mounted to one end of the head chip and having a plurality of nozzle openings corresponding to the individual ink chambers; a plurality of electrodes provided on the head chip for causing the ink to be ejected from the individual ink chambers through the nozzle openings; and a partitioning plate for creating a partition between the common ink chamber and the individual ink chambers and having a plurality of communicating holes opening to each individual ink chamber for allowing communication between the common ink chamber and the respective individual ink chambers including first communicating holes spaced from the respective nozzle openings by a distance defining a pump length of the respective individual ink chambers, the distance being set to achieve a desired print speed. 
     
     
       17. A print head according to  claim 16 ; further comprising a wiring substrate mounted to the head chip in contact with the plurality of electrodes. 
     
     
       18. A print head according to  claim 16 ; wherein the head chip comprises a piezoelectric substrate, the individual ink chambers comprise elongated grooves formed in the piezoelectric substrate, and the electrodes are disposed on sidewalls of the grooves in a longitudinal direction thereof such that a voltage applied by a respective electrode deforms a corresponding one of the individual ink chambers to cause ink contained therein to be ejected through a corresponding nozzle opening. 
     
     
       19. A print head according to  claim 16 ; wherein the head chip comprises a base plate and piezoelectric members provided on the base plate spaced by a given interval to define the respective chambers, and the electrodes are disposed on sidewalls of the piezoelectric members in a longitudinal direction thereof such that a voltage applied by a respective electrode deforms a piezoelectric member of a corresponding one of the individual ink chambers to cause ink contained therein to be ejected through a corresponding nozzle opening. 
     
     
       20. A print head according to  claim 16 ; wherein the plurality of communicating holes further comprise a second communicating hole formed near an end of the respective individual ink chambers opposite the nozzle openings.